1. Field of the Invention
The present invention relates to a one-part piston for an internal combustion engine, having a piston head and a piston skirt spaced apart from the former by a ring-shaped recess. The piston has at least one pin bore to accommodate a piston pin. A ring-shaped circumferential cooling channel for a coolant is provided in the piston head. The channel is closed off with a cover ring that consists of at least two segments. The present invention furthermore relates to a cover ring consisting of two or more segments, for the ring-shaped circumferential cooling channel of a one-part piston for an internal combustion engine.
2. The Prior Art
A piston of this type and a cover ring of this type are described in German Patent No. DE 103 46 822 A1. This piston has a ring-shaped cooling channel that is closed off, on the skirt side, by a cover ring that consists of two semi-circular half-shells. The cover ring has a groove by way of which the half-shells can be pushed onto a projection on the outside of the piston, shaped complementary to the groove shape, for the purpose of assembly. Furthermore, the half-shells have snap-in connections in the region of their join surfaces, by means of which the half-shells can be quickly connected with one another. However, the provision of the cover ring with an additional groove, and the provision of the piston with an additional projection, respectively, is complicated and therefore not desirable. Furthermore, assembly is difficult, because the two half-shells must be set onto the projections provided on the piston, in targeted manner.
Other comparable pistons are known from German Utility Model DD 252 638 A1 and German Patent No. DE 41 34 530 A1, in which a wall part that serves to cover the ring-shaped circumferential cooling channel, which is open towards the bottom, is configured as an open sheet-metal ring. The sheet-metal ring lies in a groove, against the inside circumference of the piston ring zone, or on the outside circumference of the combustion chamber wall, respectively, under bias in the radial direction.
Finally, one-part pistons having a cooling channel disposed in the edge region of the piston crown are known from European Patent Nos. EP 0 561 817 B1 and EP 0 799 373 B1, which is also closed off with cover rings configured like a plate spring and provided with a collar, if necessary.
With all of these embodiments, each segment of the spring-plate-like cover ring must be individually introduced into corresponding supports on the piston head, in the biased state.